Heat exchanger unit

ABSTRACT

The present invention relates to a heat transfer unit, in particular a charge air cooler, having a housing in which first flow channels for a gas to be cooled, and second flow channels for a cooling medium are situated separately therefrom. It is essential to the invention here that the first flow channels are made of hollow metallic bodies, each of which is sheathed with plastic on their longitudinal ends to form a shared tube bottom, wherein the second flow channels are bordered by outsides of the hollow metallic bodies, the two tube bottoms and an inside of the housing which is made of plastic.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from German Patent Application No. DE 10 2006 040 851.9, filed Aug. 31, 2006, which is hereby incorporated by reference in its entirety.

BACKGROUND

The invention relates to a heat exchanger unit, in particular a charge air cooler with a housing in which first there are flow channels for a gas to be cooled and separately therefrom there are second flow channels for a cooling medium according to the preamble of Claim 1.

Charge air coolers are used in supercharged internal combustion engines, in particular in commercial vehicles, to increase engine performance. Such a charge air cooler is arranged in the intake tract of the gasoline engine downstream from a charging device, e.g., a turbocharger.

DE 103 02 948 A1, for example, discloses a heat exchanger, in particular an exhaust gas cooler for motor vehicles equipped with flow channels arranged in a housing for a gas to be cooled and for a coolant. The flow channels for the gas pass through pipe plates into an intake and exhaust diffuser, while the coolant is carried through the housing via coolant connections. The flow channels for the gas and the coolant are formed by a shaped metal strip around the housing, in particular in a meandering pattern and joined together by bonding. The individual parts of the heat exchanger are made of metal and soldered together.

Additional heat exchanger units are known from DE 103 02 708 A1, DE 103 52 187 A1, DE 100 57 190 A1 and DE 101 46 258 A1, for example.

SUMMARY OF THE INVENTION

The present invention relates to the problem of providing an improved embodiment or at least a different embodiment for a heat transfer unit of the type defined above, so that it has a simple design and can therefore be manufactured inexpensively.

This problem is solved by a heat exchanger unit having all the features of Patent Claim 1. Advantageous and expedient embodiments of the invention are the subject of the dependent subclaims.

The invention is based on the general idea of designing a heat exchanger unit that has previously been made completely of metal and soldered together in its manufacture, so it is now made of at least two different materials, namely a metal and a plastic, wherein the metallic material is used for the first flow channels, which are sheathed plastic on their longitudinal ends to form a shared tube plate. This allows a great simplification in manufacturing the inventive heat exchanger unit, wherein only the hollow metallic bodies forming the first flow channels need be inserted into a corresponding injection mold, wherein the longitudinal ends of the metal hollow bodies are sheathed in a molded tube place encompassing all the hollow bodies. In particular this allows savings in terms of adjustment, clamping and soldering of the individual parts, which would usually be necessary with heat exchanger units made of metallic components, thus allowing the manufacturing process to be made more efficient and less expensive. In principle, the first flow channels are designed for conveyance of gas to be cooled, in particular charging air or exhaust gas, whereas second flow channels that are spatially separate are provided for transporting a cooling medium. The second flow channels are bordered by outsides of the hollow metallic bodies of the first flow channels, the two tube plates designed on the longitudinal ends of the first flow channels and by the inside of the housing made of plastic. Making the inventive heat exchanger of two different materials not only simplifies the manufacturing process of the heat exchanger unit but also permits virtually any type of shaping, in particular the second flow channels which are made mainly of plastic and/or the housing which is made of plastic, thus resulting in a great deal of structural freedom.

Two side walls of the housing are expediently integrally molded onto the two tube plates, e.g., two side walls are integrally molded together with the tube plates onto the first flow channels. Integral molding and/or simultaneous production of the side walls and the tube plates eliminates the need for assembling these individual parts subsequently, thus making it possible to improve production efficiency.

In an advantageous embodiment of the inventive approach, at least a part of the housing is a component of an intake system of an internal combustion engine. To further reduce the multitude of parts, the goal is to design one of the tube plates, a side wall or a cover and/or a bottom of the inventive heat transfer device, for example, as a connecting part to the intake system of the internal combustion engine. In this way, an especially compact design can be achieved while at the same time allowing a lighter weight, which is a great advantage, especially in view of the ever smaller amount of space available in the engine compartment.

In another advantageous embodiment of the inventive approach, the first flow channels are made of aluminum. This offers the advantage that aluminum very rapidly forms an almost impenetrable oxide layer in air, which makes the aluminum very corrosion-resistant. Since the second material used, namely plastic, does not undergo corrosion at all, a very corrosion-resistant heat transfer unit can be created on the whole by using aluminum as the lightweight metal. In addition, aluminum has a very high thermal conductivity, which is especially desired for the heat exchange in a heat transfer unit to be able to achieve efficient cooling of the charge air, for example. Of course aluminum alloys which improve the aforementioned properties and/or additionally improve processability may also be used here.

Other important features and advantages of the invention are derived from the subclaims, the drawings and the respective description of figures on the basis of the drawings.

It is self-evident that the features mentioned above and those yet to be explained below may be used not only in the particular combination given but also in other combinations or alone without going beyond the scope of the present invention.

Preferred exemplary embodiments of the invention are depicted in the drawings and explained in greater detail in the following description, where the same reference numerals are used to refer to the same or similar or functionally identical components.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show schematically,

FIG. 1 a partially cutaway view of an inventive heat transfer device,

FIG. 2 a detailed view of the sectional area of the heat transfer device according to FIG. 1,

FIG. 3 a view of a possible embodiment of the first metallic flow channels,

FIG. 4 a diagram like that in FIG. 3, but with tube plates plus side walls integrally molded onto the first flow channels at the ends.

DESCRIPTION

According to FIG. 1, an inventive heat transfer unit 1 has a housing wall 2 in which are arranged first flow channels 3 for the gas to be cooled, in particular charge air or exhaust gas, and separately therefrom, second flow channels 4 for a cooling medium (see also FIG. 2). In the present case, the heat transfer unit 1 is designed as a charge air cooler as an example. Such a charge air cooler is usually provided for increasing the performance of a combustion engine and, by cooling the intake air after it is compressed by a charging device and/or a compressor, the quantity of air entering the cylinder with the intake is such that more fuel can be burned per working cycle at a given fuel/air ratio.

According to this invention, the first flow channels 3 consist of hollow metallic bodies which are sheathed in plastic on their longitudinal end sides 5, 5′ to form a shared tube plate 6, 6′. The second flow channels 4 are bordered by the outsides of the hollow metallic bodies, the two tube plates 6, 6′ and an inside of the housing 2, which is otherwise made of plastic.

In contrast with traditional heat transfer devices, the heat transfer unit 1 according to this invention is made of at least two different materials, namely metal and plastic, so that the manufacturing and/or finishing process of the inventive heat transfer unit 1 is greatly simplified and is therefore less expensive. In particular, this eliminates any complicated adjustment, fixation and then soldering of the individual parts of the heat transfer unit. It is also conceivable here that in sheathing the longitudinal ends 5, 5′ of the first flow channels 3, not only the tube plates 6, 6′ but at the same time also two side walls 7, 7′ joining the two tube plates 6, 6′ are manufactured together in one operation with the injection of the two tube plates 6, 6′. For finishing housing 2, which in addition to the two tube plates 6, 6′ and the two side walls 7, 7′ also comprises a cover 8 and a bottom 9, thus only the cover 8 and the bottom 9 are each to be joined to the tube plates 6, 6′ and/or to the side walls 7, 7′. Such a connection may be established, for example, by gluing or by means of a friction weld that is resistant to both coolants and temperatures.

As shown in FIG. 1, both the cover 8 and the bottom 9 each have a cooling medium connection 10, 10′ by means of which the heat transfer unit 1 can be connected to a coolant circuit. Such a cooling medium connection 10, 10′ may be designed, for example, in the manner of a traditional male or female connection or the like. To be able to reduce the multitude of parts in addition to simplifying the manufacturing process of the inventive heat transfer unit 1, the cover 8 and the bottom 9 are preferably designed as identical parts and therefore mav be used both as the bottom 9 and as the cover 8.

The heat transfer unit 1 is under the pressure of the cooling medium flowing in the heat transfer unit 1 during operation, so reinforcing elements 11, e.g., flanging, may be provided on the cover 8 and/or on the bottom 9. As an alternative or in addition, it is also conceivable for the cover 8 to be connected to the bottom 9 by at least one web (not shown) capable of withstanding tensile stress. Such a web as well as at least one reinforcing element 11, as mentioned above, limit deformation of the cover 8 and/or the bottom 9, which is induced under some circumstances by the coolant pressure in the interior of the heat transfer unit 1. Such reinforcing elements 11 may of course also be arranged on the side walls 7, 7′ and may therefore limit deformation thereof.

A sealing element 13 which additionally supports a seal between the first flow channels 3 and the second flow channels 4 is provided at the longitudinal end of the first flow channels 3. Such a sealing element 13 may be made of a TPE plastic (thermoplastic elastomer or thermal polyethylene), for example. On the other hand, the housing 2, in particular the tube plates 6, 6′ and the side walls 7, 7′ are made of a polyamide, i.e., nylon. The TPE plastic is necessary for the sealing element 13 to achieve a tight seal between the surface of the first flow channels 3, i.e., between the surface of the hollow bodies and the integrally molded tube plates 6, 6′ because the polyamide cannot be attached directly to metal. From a manufacturing standpoint, the sealing element 13 can be produced either before or after integral molding of the tube plates 6, 6′ onto the longitudinal ends 5, 5′ of the first flow channels 3.

As shown in FIG. 3, the first flow channels 3 run parallel to one another and have a rectangular cross section that is rounded in the corner areas. All the first flow channels 3 shown here have the same cross section and the same length, so it is conceivable that a hollow body designed as bar stock could be cut to the proper length to produce the first flow channels 3 and the individual pieces later arranged parallel to one another, e.g., by means of a comb-like adjusting device.

FIG. 4 shows the hollow bodies arranged parallel to one another, whereby their longitudinal ends 5, 5′ are already sheathed in plastic to form a shared tube plate 6, 6′. As mentioned above, the side walls 7, 7′ are preferably manufactured in the same step of the operation in which the integral molding and/or sheathing of the longitudinal ends 5, 5′ of the first channels 3 to the tube plate 6, 6′ takes place.

To be able to further reduce the multitude of parts, it is also conceivable for at least a portion of the housing 2 to be a part of an intake system (not shown) of an internal combustion engine, whereby in particular the cover 8, the bottom 9 or one of the tube plates 6, 6′ may be part of the intake system at the same time. Such an embodiment ensures an especially compact design of the inventive heat transfer device 1 and, as mentioned above, reduces the multitude of parts and thereby also lowers costs.

To be able to additionally increase the heat transfer between the gas that is to be cooled and the cooling medium, the hollow bodies, i.e., the first flow channels 3 are preferably made of aluminum which is characterized by a high thermal conductivity on the one hand and also by a high corrosion resistance on the other hand. In addition, aluminum is very lightweight, which has a positive effect on the energy balance of the motor vehicle. In addition to the use of a suitable material, i.e., in particular a material with a high thermal conductivity, additional heat transfer elements 12 may also be arranged inside the first flow channels 3, these heat transfer elements being inserted, for example, into the first flow channels 3 after sheathing of the longitudinal ends 5, 5′ of the first flow channels 3 with the tube plates 6, 6′ and then connected thereto in a thermally conducting manner. Heat conducting films, in particular running in a meandering pattern between two side walls of the first flow channels 3, may be considered here as the heat transfer elements 12. 

1. A heat transfer unit, in particular a charge air cooler, having a housing in which first flow channels for gas to be cooled and separate second flow channels for a cooling medium are situated, wherein the first flow channels are made of hollow metallic bodies which are sheathed with plastic on each of their longitudinal ends to form a shared tube bottom, the second flow channels are bordered by outsides of the hollow metallic bodies, the two tube bottoms and an inside of the housing which is made of plastic.
 2. The heat transfer unit according to claim 1, wherein the housing comprises the two tube bottoms, two side walls, a cover and a bottom, whereby the cover and the bottom each have a cooling medium connection.
 3. The heat transfer unit according to claim 1, wherein two side walls of the housing joining the two tube bottoms to one another are integrally molded onto the two tube bottoms.
 4. The heat transfer unit according to claim 1, wherein two side walls of the housing joining the two tube bottoms together are manufactured together with the tube bottoms by injection molding.
 5. The heat transfer unit according to claim 2, wherein the cover and/or the bottom is/are welded to the remaining housing.
 6. The heat transfer unit according to claim 1, wherein at least a part of the housing is a component of an intake system of an internal combustion engine.
 7. The heat transfer unit according to claim 1, wherein the first flow channels are made of aluminum.
 8. The heat transfer unit according to claim 1, wherein the first flow channels have a rectangular cross section.
 9. The heat transfer unit according to claim 1, wherein the first flow channels have the same cross section and/or the same length.
 10. The heat transfer unit according to claim 1, wherein heat transfer elements are arranged inside the hollow bodies of the first flow channels.
 11. The heat transfer unit according to claim 2, wherein the cover and the bottom are designed as identical parts.
 12. The heat transfer unit according to claim 1, wherein the first flow channels run parallel to one another.
 13. The heat transfer unit according to claim 2, wherein the cover and/or the bottom has/have at least one reinforcing element.
 14. The heat transfer unit according to claim 2, wherein the cover is connected to the bottom by at least one web. 